This work has been supported by NIH HL-1034.

L&#39;Università di cura e utilizzo Comitato Animal Johns Hopkins ha approvato tutti i protocolli di animali. 1. apparecchiature Il sistema composito costituito, pronti per misurare la curva PV è mostrato in Figura 1. <ol><li> Misura Volume: <ol><li> Generare un tasso costante di gonfiaggio e sgonfiaggio utilizzando una pompa a siringa con un interruttore che consente all&#39;utente di invertire rapidamente la pompa dopo aver raggiunto i limiti di pressione. Per le curve del mouse FV, utilizzare un molto leggermente unta siringa di vetro 5 ml con il volume iniziale (prima di inflazione) fissato a 3 ml di aria. 3 ml è sufficientemente ampio per misurare i volumi in quasi tutte le curve del mouse fotovoltaici. </li><li> Misurare il volume erogato dalla pompa collegando un trasformatore differenziale lineare al corpo pompa, con una piccola asta sensore collegato alla siringa movimento stantuffo. Nota: Un mezzo empirici per correggere per la compressione del gas nel sistema è descritto sotto il cu PVsezione registrazione rve. </li></ol></li><li> Misurazione della pressione: <ol><li> Utilizzare un manometro economico standard con una gamma di 0-60 cm H 2 O (0-1 PSI). </li></ol></li><li> Misura di registrazione: <ol><li> Per registrare la curva PV utilizzare qualsiasi registratore digitale con funzionalità XY (ad esempio, Powerlab). Impostare un canale per registrare il segnale volume corretto e un altro canale per registrare la pressione transpolmonare (PTP), al fine di rappresentare graficamente la curva PV. Utilizzare un preamplificatore ponte che collega alla Powerlab principale per misurare la pressione. Calibrare il canale di pressione 0-40 cm H 2 O, e calibrare il canale del volume da 0-3 ml. </li></ol></li></ol> 2. Correzione per Compressione Gas Nota: Questa è una fase critica iniziale nel set up, poiché, come la pressione aumenta, diminuisce di volume di gas, e quindi il volume d&#39;aria erogata al mouse sarà sempre inferiore lo spostamento del syringe barile. <ol><li> Chiudere il rubinetto che collegherà l&#39;impianto fotovoltaico ai polmoni, in modo che nessun gas può lasciare il sistema. Avviare l&#39;infusione e osservare se il canale Volume corretto sul registratore mostra eventuali cambiamenti misurabili come la pressione aumenta a circa 40 cm H 2 O. Se è così, allora preciso nei passaggi successivi. <ol><li> Corretta per la compressione del gas empiricamente sottraendo dalla misura dello spostamento dello stantuffo (cioè, il volume non corretta) un termine proporzionale alla pressione di gonfiaggio. Effettuare questa operazione su un canale Powerlab (chiamato Vc) per mostrare il segnale volume di meno di un coefficiente volte la pressione. </li><li> Determinare il coefficiente nell&#39;equazione. In primo luogo, fare un tentativo iniziale, ruotare il grafico registrazione su, e avviare la pompa. Poiché il tubo di gonfiaggio è sigillato, regolare il moltiplicatore coefficiente di pressione per rendere il canale Vc leggere zero la pressione sale 0-40 cm H 2 O. Se si va su o giù, semplicemente regolare il fattore di correzione fino arimane piatta su questo campo di pressione. Questo fattore di correzione sarà sempre la stessa, se le stesse 3 ml partire volume nella siringa non è cambiato. </li></ol></li></ol> 3. Le prove sperimentali in topi <ol><li> Procedura per la misurazione della curva PV nei topi. Tutti i protocolli di animali sono stati approvati dall&#39;Università Cura e uso Comitato Animal Johns Hopkins. <ol><li> Anestetizzare topi (C57BL / 6 topi a 6-12 settimane di età) con ketamina (90 mg / kg) e xilazina (15 mg / kg), e confermare l&#39;anestesia dall&#39;assenza di movimento riflesso. Nota: La curva PV può essere completato in topi anestetizzati in meno di 10 minuti ed è una procedura terminale. </li><li> Tracheostomize i topi con un 18 G stub ago cannula. A tale scopo, una piccola incisione nella pelle sovrastante la trachea, localizzare la trachea, poi facendo una piccola fessura nella trachea, in cui l&#39;ago stub può essere inserito. Fissare la cannula legando con filo. </li><li> Lasciare i topi a respirare 100% di ossigeno per almeno 4 min. Questo può avvenire tramite la respirazione spontanea da un sacchetto o con un ventilatore nominalmente impostato con un volume corrente di 0,2 ml a 150 respiri / min. </li><li> Chiudere la cannula tracheale e lasciare 3-4 min per il mouse di assorbire tutto l&#39;ossigeno. Questa procedura assorbimento di ossigeno risulta la morte degli animali e in un degasaggio quasi completa del polmone 11. Conferma morte del mouse misurando la cessazione del battito cardiaco con elettrodi ECG o osservazione diretta. </li><li> Una volta che il degasaggio del polmone è completa e il volume polmonare è zero, cominciare a gonfiare il polmone con aria ambiente nella pompa a siringa ad una velocità di 3 ml / min. Monitorare la traccia pressione sul registratore digitale, e quando raggiunge i 35 cm H 2 O, invertire la pompa. </li><li> Seguire la curva di deflazione fino pressione raggiunge negativo del 10 cm H 2 O, momento in cui le vie aeree sono crollati, intrappolando l&#39;aria in alveoli che impediscono un&#39;ulteriore riduzione del volume. Invertire immediatamente tegli pompa di nuovo, consentendo al polmone per rigonfiare le vie respiratorie crollati aprire. Questa apertura eterogenea è normalmente evidenti dalla rumorosa dell&#39;arto gonfiaggio guardando la parte iniziale di questo 2a gonfiaggio. </li><li> Quando la pressione raggiunge nuovamente 35 centimetri H 2 O, invertire la direzione della pompa, e continuare a sgonfiare il polmone fino a questo 2a sgonfiaggio arto raggiunge 0 cm H 2 O. Quindi fermare la pompa. </li><li> Visualizza il record grafico PowerLab di pressione e portata e la curva PV. Poi analizza la curva PV per rilevare i cambiamenti fenotipici di parenchima polmonare che si verificano con diverse patologie polmonari. </li></ol></li></ol>

<ol>
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None of the authors have any financial interests that would be in conflict with the material presented in this paper.

In questo documento un metodo semplice e riproducibile è stato descritto per misurare in topi un metodo classico di elasticità fenotipizzazione polmonare, la curva totale PV polmonare. Tali curve sono state fondamentali per la scoperta del surfattante polmonare e la sua importanza nel fornire stabilità al polmone. Qui è mostrato come la curva PV è anche utile nel fornire un mezzo per misurare diverse variabili collegati elasticità polmonare nei polmoni topo adulto. Ci sono stati cambiamenti molto significativi in ...

Il mouse è ora il modello animale primario di una varietà di malattie polmonari. Nei modelli di enfisema o fibrosi, i cambiamenti fenotipici essenziali sono meglio valutati misurando le variazioni di elasticità polmonare. Sebbene vi siano molti modi per misurare l&#39;elasticità, il metodo classico è quello della curva di pressione-volume totale (PV) misurata dal volume residuo (RV) alla capacità polmonare totale (TLC). Questa misura è stata fatta su polmoni adulti da quasi tutte le specie di mammiferi risalenti quasi 100 anni 1-3. Tali curve PV anche svolto un ruolo importante nella scoperta e la comprensione della funzione del surfattante polmonare nello sviluppo del polmone fetale 4-7. Nonostante l&#39;importanza della curva PV come misura del fenotipo del polmone, non vi è stato alcun modo standardizzato effettuare tale misurazione. E &#39;stato fatto semplicemente gonfiando e sgonfiando polmone con passi discreti (attesa per un tempo variabile equilibramento dopo ogni) o con pompepuò continuamente gonfiare e sgonfiare il polmone. La curva PV è spesso fatto in un intervallo di volume tra zero e alcune capacità polmonare dall&#39;utente definire, ma la durata di ogni ciclo pressione volume riportato da diversi laboratori è estremamente variabile, che varia da pochi secondi a 8 ore 2. Alcuni ricercatori si riferiscono a questa curva totale PV polmone come statico o quasi statica, ma questi sono termini qualitativi che offrono visione poco, e che non sono usati qui. Inoltre, la curva PV non è stato ampiamente riportato nel topo, nonostante il fatto che essa può fornire informazioni utili sugli effetti macroscopici di cambiamenti strutturali nel polmone. Diversi problemi hanno portato a variabilità acquisizione curva PV tra cui: 1) il tasso di inflazione e la deflazione; 2) le escursioni di pressione per l&#39;inflazione e la deflazione; e 3) mezzi per la determinazione di una misura assoluta volume polmonare. Nel metodo qui presenti, una velocità di 3 ml / min è stato scelto come compromise, non essendo troppo breve da riflettere l&#39;elasticità dinamica associata con ventilazione normale e non troppo lento da rendere impraticabile la misura, in particolare quando si studia grandi coorti. Poiché una capacità nominale polmonare totale in un C57BL / 6 sana mouse è dell&#39;ordine di 1,2 ml 9, questo tasso consente tipicamente due completo chiusi PV cicli essere fatto in circa 1,5 min. In letteratura estesa in cui sono state riportate le curve PV, la pressione di gonfiaggio di picco utilizzato è stato estremamente variabile, variando da un minimo di 20 ad oltre 40 cm H 2 O. Una parte di questa variabilità può essere correlato alla specie, ma un obiettivo primario di impostare il limite di pressione superiore per le curve PV è di gonfiare il polmone di capacità totale polmonare (TLC), o il volume polmonare massimo. La TLC nell&#39;uomo è definita dallo sforzo massimale volontaria un individuo può fare, ma purtroppo non può mai essere duplicato in qualsiasi modello animale. Così, il volume massimo in curve sperimentali FV è scoraggiareminato da una pressione massima fissato arbitrariamente dallo sperimentatore. L&#39;obiettivo è quello di impostare una pressione in cui la curva PV è piatta, ma purtroppo l&#39;arto inflazione di una curva PV polmone dei mammiferi non è mai piatta. Quindi molti ricercatori impostare una pressione in cui la curva di gonfiaggio inizia ad appiattirsi sostanzialmente, genere il 30 cm H 2 O. Nel topo, tuttavia, la curva PV è ancora più complessa con una doppia gobba sull&#39;arto gonfiaggio, e dove tale parte dell&#39;inflazione spesso ancora a picco al 30 cm H 2 O 10, quindi 30 non è un punto finale per il buon curva PV. Per questo motivo, usiamo 35 centimetri H 2 O come il limite di pressione per la curva del mouse PV, che è una pressione alla quale gli arti gonfiaggio di tutti i ceppi che abbiamo esaminato cominciano ad appiattirsi. Poiché la curva PV è molto lineare, l&#39;aspetto di un loop PV dipenderà dal volume da dove la curva inizia. Alcuni ventilatori commerciali consentono agli utenti di fare grandi anse fotovoltaici, partendo da FRC, ma se il volume FRC è sconosciuto, allora è impossibile interpretare variazioni di tale curva PV con qualsiasi patologia, poiché questi cambiamenti potrebbero semplicemente derivare da un cambiamento di volume di partenza, e non alterazioni strutturali nel polmone. Così, senza una misura del volume assoluto, curve PV sono quasi impossibili da interpretare e quindi hanno scarsa utilità. Anche se, ci sono diversi modi per misurare i volumi polmonari, questi sono spesso ingombranti e richiedono attrezzature speciali. Nella semplice metodo qui descritto, la curva PV inizia a volume zero dopo una procedura di degasaggio in vivo. In sintesi, questo lavoro dimostra un metodo semplice per standardizzare la misurazione della curva PV polmonare nel polmone del mouse, e definisce alcuni parametri che possono essere calcolati da questa curva che sono collegate alla struttura del polmone. La curva PV fornisce quindi un test di funzionalità polmonare, che ha applicazione diretta di essere in grado di rilevare i cambiamenti strutturali fenotipiche nei topi con commsulle patologie polmonari come l&#39;enfisema e fibrosi.

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			<td height="21" style="height:21px;width:244px;">Name of Material/ Equipment</td>
			<td style="width:127px;">Company</td>
			<td style="width:155px;">Catalog Number</td>
			<td style="width:167px;">Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;"></td>
			<td style="width:127px;"></td>
			<td style="width:155px;"></td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:244px;"></td>
			<td style="width:127px;"></td>
			<td style="width:155px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:244px;">&#160;Syringe Pump</td>
			<td style="width:127px;">Harvard Apparatus</td>
			<td>55-2226</td>
			<td>Infuse/Withdraw syringe pump</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Pump 22 Reversing Switch&#160;</td>
			<td style="width:127px;">Harvard Apparatus</td>
			<td>552217</td>
			<td>&#160;included with pump</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;"></td>
			<td style="width:127px;"></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;">Linear displacement transformer</td>
			<td style="width:127px;">Trans-Tek, Inc.</td>
			<td style="width:155px;">0244-0000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;"></td>
			<td style="width:127px;"></td>
			<td style="width:155px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;">5 mL glass syringe</td>
			<td style="width:127px;">Becton Dickenson</td>
			<td style="width:155px;"></td>
			<td>Several other possible vendors</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;"></td>
			<td style="width:127px;"></td>
			<td style="width:155px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;">Digital recorder</td>
			<td style="width:127px;">ADInstruments</td>
			<td>PL3504</td>
			<td>Several other possible vendors</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Bridge Amp Signal Conditioner</td>
			<td style="width:127px;">ADInstruments</td>
			<td>FE221</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;"></td>
			<td style="width:127px;"></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;">Gas tank,100% oxygen</td>
			<td style="width:127px;">Airgas, Inc</td>
			<td style="width:155px;"></td>
			<td>Any supplier or hospital source will work</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;"></td>
			<td style="width:127px;"></td>
			<td style="width:155px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pressure Transducer - 0-1psi&#160; millivolt output</td>
			<td>Omega Engineering</td>
			<td>PX-137</td>
			<td>Range: &#8776;0-60 cmH2O</td>
		</tr>
	</tbody>
</table>

measurement of the pressure-volume curve in mouse lungs

Negli ultimi decenni topo è diventato il modello animale primario di una varietà di malattie polmonari. Nei modelli di enfisema o fibrosi, le variazioni fenotipiche essenziali sono meglio valutati mediante misurazione delle variazioni di elasticità polmonare. Per comprendere meglio i meccanismi specifici alla base di tali patologie nei topi, è indispensabile effettuare misurazioni funzionali che possono riflettere la patologia sviluppo. Sebbene vi siano molti modi per misurare l&#39;elasticità, il metodo classico è quello del polmone pressione volume totale (PV) Curva fatto sull&#39;intero intervallo di volumi polmonari. Questa misura è stata fatta su polmoni adulti da quasi tutte le specie di mammiferi risalenti quasi 100 anni, e tali curve fotovoltaici anche svolto un ruolo importante nella scoperta e la comprensione della funzione del surfattante polmonare in sviluppo polmonare fetale. Purtroppo, tali curve totale PV non sono stati ampiamente riportati nel topo, nonostante il fatto che essi possono fornire informazioni utili sul macroscEffetti OPIC di cambiamenti strutturali nel polmone. Sebbene curve parziali FV misura solo le variazioni di volume polmonare sono talvolta riportati, senza misura del volume assoluto, la natura non lineare della curva totale PV rende questi parziali molto difficile interpretazione. Nel presente studio, si descrive un metodo standardizzato per misurare la curva totale PV. Abbiamo poi testato la capacità di queste curve per rilevare i cambiamenti nella struttura del polmone del mouse in due patologie polmonari comuni, enfisema e fibrosi. I risultati hanno mostrato cambiamenti significativi in ​​più variabili coerenti con i cambiamenti strutturali attesi con queste patologie. Questa misurazione della curva PV polmone nei topi fornisce pertanto un mezzo semplice per monitorare la progressione dei cambiamenti fisiopatologici nel tempo e l&#39;effetto potenziale di procedure terapeutiche.

Anche se la procedura per le curve FV è dimostrato nel video solo per topi sani di controllo, abbiamo esaminato la capacità della curva PV per rilevare cambiamenti funzionali e patologici in topi con due diverse patologie comuni, enfisema e fibrosi. I dettagli di questi modelli tradizionali descritte altrove 12,13. Molto brevemente, dopo l&#39;anestesia con il 3% isoflurano l&#39;enfisema è stato causato da 3 o 6 U elastasi pancreatica porcina instillato nella trachea e ha studiato tre settimane più tardi...

Watch this Scientific Journal Video about Measurement of the Pressure-volume Curve in Mouse Lungs at JoVE.com

Measurement of the Pressure-volume Curve in Mouse Lungs

Here we present a protocol to simply and reliably measure the lung pressure-volume curve in mice, showing that it is sufficiently sensitive to detect phenotypic parenchymal changes in two common lung pathologies, pulmonary fibrosis and emphysema. This metric provides a means to quantify the lung&#8217;s structural changes with developing pathology.

Misura della curva di pressione-volume in mouse polmoni

In recent decades the mouse has become the primary animal model of a variety of lung diseases. In models of emphysema or fibrosis, the essential ...

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18.5K Views.  Johns Hopkins University. Here we present a protocol to simply and reliably measure the lung pressure-volume curve in mice, showing that it is sufficiently sensitive to detect phenotypic parenchymal changes in two common lung pathologies, pulmonary fibrosis and emphysema. This metric provides a means to quantify the lung’s structural changes with developing pathology.

Video: Measurement of the Pressure-volume Curve in Mouse Lungs

The Measurement and Treatment of Suppression in Amblyopia

Amblyopia, a developmental disorder of the visual cortex, is one of the leading causes of visual dysfunction in the working age population. Current estimates put the prevalence of amblyopia at approximately 1-3%1-3, the majority of cases being monocular2. Amblyopia is most frequently caused by ocular misalignment (strabismus), blur induced by unequal refractive error (anisometropia), and in some cases by form deprivation.
Although amblyopia is initially caused by abnormal visual input in infancy, once established, the visual deficit often remains when normal visual input has been restored using surgery and/or refractive correction. This is because amblyopia is the result of abnormal visual cortex development rather than a problem with the amblyopic eye itself4,5 . Amblyopia is characterized by both monocular and binocular deficits6,7 which include impaired visual acuity and poor or absent stereopsis respectively. The visual dysfunction in amblyopia is often associated with a strong suppression of the inputs from the amblyopic eye under binocular viewing conditions8. Recent work has indicated that suppression may play a central role in both the monocular and binocular deficits associated with amblyopia9,10 .
Current clinical tests for suppression tend to verify the presence or absence of suppression rather than giving a quantitative measurement of the degree of suppression. Here we describe a technique for measuring amblyopic suppression with a compact, portable device11,12 . The device consists of a laptop computer connected to a pair of virtual reality goggles. The novelty of the technique lies in the way we present visual stimuli to measure suppression. Stimuli are shown to the amblyopic eye at high contrast while the contrast of the stimuli shown to the non-amblyopic eye are varied. Patients perform a simple signal/noise task that allows for a precise measurement of the strength of excitatory binocular interactions. The contrast offset at which neither eye has a performance advantage is a measure of the "balance point" and is a direct measure of suppression. This technique has been validated psychophysically both in control13,14 and patient6,9,11 populations.
In addition to measuring suppression this technique also forms the basis of a novel form of treatment to decrease suppression over time and improve binocular and often monocular function in adult patients with amblyopia12,15,16 . This new treatment approach can be deployed either on the goggle system described above or on a specially modified iPod touch device15.

Amblyopia is a developmental disorder of the visual cortex that is often accompanied by strong suppression of one eye. We present a new technique for measuring and treating interocular suppression in patients with amblyopia that can be deployed using virtual reality goggles or a portable iPod Touch device.

La misurazione e trattamento di soppressione in Ambliopia

Amblyopia, a developmental disorder of the visual cortex, is one of the leading causes of visual dysfunction in the working age population. Current ...

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In vivo Measurement of the Mouse Pulmonary Endothelial Surface Layer

The endothelial glycocalyx is a layer of proteoglycans and associated glycosaminoglycans lining the vascular lumen. In vivo, the glycocalyx is highly hydrated, forming a substantial endothelial surface layer (ESL) that contributes to the maintenance of endothelial function. As the endothelial glycocalyx is often aberrant in vitro and is lost during standard tissue fixation techniques, study of the ESL requires use of intravital microscopy. To best approximate the complex physiology of the alveolar microvasculature, pulmonary intravital imaging is ideally performed on a freely-moving lung. These preparations, however, typically suffer from extensive motion artifact. We demonstrate how closed-chest intravital microscopy of a freely-moving mouse lung can be used to measure glycocalyx integrity via ESL exclusion of fluorescently-labeled high molecular weight dextrans from the endothelial surface. This non-recovery surgical technique, which requires simultaneous brightfield and fluorescent imaging of the mouse lung, allows for longitudinal observation of the subpleural microvasculature without evidence of inducing confounding lung injury.

In vivo Measurement of the Mouse Pulmonary Endothelial Surface Layer

The endothelial glycocalyx/endothelial surface layer is ideally studied using intravital microscopy. Intravital microscopy is technically challenging in a moving organ such as the lung. We demonstrate how simultaneous brightfield and fluorescent microscopy may be used to estimate endothelial surface layer thickness in a freely-moving in vivo mouse lung.

Nella misura in vivo della superficie polmonare strato endoteliale mouse

The endothelial glycocalyx is a layer of proteoglycans and associated glycosaminoglycans lining the vascular lumen. In vivo, the glycocalyx is highly ...

Technical Aspects of the Mouse Aortocaval Fistula

Technical aspects of creating an arteriovenous fistula in the mouse are discussed. Under general anesthesia, an abdominal incision is made, and the aorta and inferior vena cava (IVC) are exposed. The proximal infrarenal aorta and the distal aorta are dissected for clamp placement and needle puncture, respectively. Special attention is paid to avoid dissection between the aorta and the IVC. After clamping the aorta, a 25 G needle is used to puncture both walls of the aorta into the IVC. The surrounding connective tissue is used for hemostatic compression. Successful creation of the AVF will show pulsatile arterial blood flow in the IVC. Further confirmation of successful AVF can be achieved by post-operative Doppler ultrasound.

The goal is to produce an arteriovenous fistula that is simple and reproducible. This method does not use sutures or glue adhesive. Therefore the samples can be used with the least amount of foreign materials for analysis.

Aspetti tecnici della fistola aorto-cavale mouse

Technical aspects of creating an arteriovenous fistula in the mouse are discussed. Under general anesthesia, an abdominal incision is made, and the aorta ...

Myocardial Infarction and Functional Outcome Assessment in Pigs

Introduction of newly discovered cardiovascular therapeutics into first-in-man trials depends on a strictly regulated ethical and legal roadmap. One important prerequisite is a good understanding of all safety and efficacy aspects obtained in a large animal model that validly reflect the human scenario of myocardial infarction (MI). Pigs are widely used in this regard since their cardiac size, hemodynamics, and coronary anatomy are close to that of humans. Here, we present an effective protocol for using the porcine MI model using a closed-chest coronary balloon occlusion of the left anterior descending artery (LAD), followed by reperfusion. This approach is based on 90 min of myocardial ischemia, inducing large left ventricle infarction of the anterior, septal and inferoseptal walls. Furthermore, we present protocols for various measures of outcome that provide a wide range of information on the heart, such as cardiac systolic and diastolic function, hemodynamics, coronary flow velocity, microvascular resistance, and infarct size. This protocol can be easily tailored to meet study specific requirements for the validation of novel cardioregenerative biologics at different stages (i.e. directly after the acute ischemic insult, in the subacute setting or even in the chronic MI once scar formation has been completed). This model therefore provides a useful translational tool to study MI, subsequent adverse remodeling, and the potential of novel cardioregenerative agents.

This protocol describes the porcine myocardial infarction (MI) model using a 90 min closed-chest coronary balloon occlusion of the left anterior descending artery (LAD), followed by reperfusion. Furthermore, the protocol for several outcome parameters, such as cardiac function, hemodynamics, microvascular resistance, and infarct size, are also presented.

Infarto miocardico e funzionale Outcome Assessment in Pigs

Introduction of newly discovered cardiovascular therapeutics into first-in-man trials depends on a strictly regulated ethical and legal roadmap. One ...

Cardiac Catheterization in Mice to Measure the Pressure Volume Relationship: Investigating the Bowditch Effect

Animal models that mimic human cardiac disorders have been created to test potential therapeutic strategies. A key component to evaluating these strategies is to examine their effects on heart function. There are several techniques to measure in vivo cardiac mechanics (e.g., echocardiography, pressure/volume relations, etc.). Compared to echocardiography, real-time left ventricular (LV) pressure/volume analysis via catheterization is more precise and insightful in assessing LV function. Additionally, LV pressure/volume analysis provides the ability to instantaneously record changes during manipulations of contractility (e.g., &#946;-adrenergic stimulation) and pathological insults (e.g., ischemia/reperfusion injury). In addition to the maximum (+dP/dt) and minimum (-dP/dt) rate of pressure change in the LV, an accurate assessment of LV function via several load-independent indexes (e.g., end systolic pressure volume relationship and preload recruitable stroke work) can be attained. Heart rate has a significant effect on LV contractility such that an increase in the heart rate is the primary mechanism to increase cardiac output (i.e., Bowditch effect). Thus, when comparing hemodynamics between experimental groups, it is necessary to have similar heart rates. Furthermore, a hallmark of many cardiomyopathy models is a decrease in contractile reserve (i.e., decreased Bowditch effect). Consequently, vital information can be obtained by determining the effects of increasing heart rate on contractility. Our and others data has demonstrated that the neuronal nitric oxide synthase (NOS1) knockout mouse has decreased contractility. Here we describe the procedure of measuring LV pressure/volume with increasing heart rates using the NOS1 knockout mouse model.

This article describes the measurement of murine left ventricular function via pressure/volume analysis at different heart rates.

Cateterizzazione cardiaca nei topi per misurare il rapporto pressione del volume: Indagare l&#39;effetto Bowditch

Animal models that mimic human cardiac disorders have been created to test potential therapeutic strategies. A key component to evaluating these ...

Preparation Steps for Measurement of Reactivity in Mouse Retinal Arterioles Ex Vivo

Vascular insufficiency and alterations in normal retinal perfusion are among the major factors for the pathogenesis of various sight-threatening ocular diseases, such as diabetic retinopathy, hypertensive retinopathy, and possibly glaucoma. Therefore, retinal microvascular preparations are pivotal tools for physiological and pharmacological studies to delineate the underlying pathophysiological mechanisms and to design therapies for the diseases. Despite the wide use of mouse models in ophthalmic research, studies on retinal vascular reactivity are scarce in this species. A major reason for this discrepancy is the challenging isolation procedures owing to the small size of these retinal blood vessels, which is ~ &#8804; 30 &#181;m in luminal diameter. To circumvent the problem of direct isolation of these retinal microvessels for functional studies, we established an isolation and preparation technique that enables ex vivo studies of mouse retinal vasoactivity under near-physiological conditions. Although the present experimental preparations will specifically refer to the mouse retinal arterioles, this methodology can readily be employed to microvessels from rats.

Preparation Steps for Measurement of Reactivity in Mouse Retinal Arterioles Ex Vivo

Many vision-threatening ocular diseases are associated with dysfunctional retinal microvessels. Therefore, the measurement of retinal arteriole responses is important to investigate the underlying pathophysiological mechanisms. This article describes a detailed protocol for mouse retinal arteriole isolation and preparation to assess the effects of vasoactive substances on vascular diameter.

Procedura di preparazione per la misura della reattività in Mouse arteriole retiniche Ex Vivo

Vascular insufficiency and alterations in normal retinal perfusion are among the major factors for the pathogenesis of various sight-threatening ocular ...

Real-time Pressure-volume Analysis of Acute Myocardial Infarction in Mice

Acute myocardial infarction can lead to acute heart failure and cardiogenic shock. The evaluation of hemodynamics is critical for the evaluation of any potential therapeutic approach directed against acute left ventricular (LV) dysfunction. Current imaging modalities (e.g., echocardiography and magnetic resonance imaging) have several limitations since data on LV pressure cannot directly be measured. LV catheterization in mice undergoing coronary artery occlusion could serve as a novel method for a real-time evaluation of LV function.
At the beginning of the procedure, mice were anesthetized followed by endotracheal intubation. For LV catheterization, the right carotid artery was exposed via middle-neck incision. The catheter was introduced and placed into the LV cavity. Left thoracotomy was conducted and the left main coronary artery (LCA) was ligated. To induce reperfusion, the suture was released after 45 min. Pressure-volume data was recorded at all times.
Ligation of the LCA caused a decrease in LV systolic function as evidenced by a 30% reduction in stroke volume, LV ejection fraction (EF), and cardiac output. Maximum dP/dt as a parameter for LV contractility was also significantly reduced and diastolic function was severely impaired (minimum dP/dt -40%). Reperfusion over a period of 20 min did not lead to a complete recovery of LV function.
Real-time pressure-volume analysis served as a valid procedure for monitoring cardiac function during acute myocardial infarction in mice. Maintaining stable anesthesia and a standardized surgical approach was crucial to ensure valid results. As the early phase of acute myocardial infarction is critical for morbidity and mortality, the delineated method could be beneficial for preclinical evaluation of new strategies for cardioprotection.

Acute myocardial infarction in mice induces acute but incompletely characterized changes in left ventricular (LV) function. LV catheterization in mice undergoing coronary artery occlusion serves as a novel method for a real-time evaluation of LV function.

Analisi in tempo reale pressione-volume di infarto miocardico acuto nei topi

Acute myocardial infarction can lead to acute heart failure and cardiogenic shock. The evaluation of hemodynamics is critical for the evaluation of any ...

Echocardiographic Measurement of Right Ventricular Diastolic Parameters in Mouse

Diastolic dysfunction is a prominent feature of right ventricular (RV) remodeling associated with conditions of pressure overload. However, the RV diastolic function is rarely quantified in experimental studies. This might be due to technical difficulties in the visualization of the RV in the apical four-chamber view in rodents. Here we describe two positions facilitating the visualization of the apical four-chamber view in mice to assess the RV diastolic function.
The apical four-chamber view is enabled by tilting the mouse fixation platform to the left and caudally (LeCa) or to the right and cranially (RiCr). Both positions provide images of comparable quality. The results of the RV diastolic function obtained from two positions are not significantly different. Both positions are comparably easy to perform. This protocol can be incorporated into published protocols and enables detailed investigations of the RV function.

Here we describe and compare two positions for obtaining the apical four-chamber view in mice. These positions enable the quantification of the right ventricular function, provide comparable results, and can be used interchangeably.

Misurazione ecocardiografica dei parametri diastolici ventricolari a destra nel mouse

Diastolic dysfunction is a prominent feature of right ventricular (RV) remodeling associated with conditions of pressure overload. However, the RV ...

Isometric Contractility Measurement of the Mouse Mesenteric Artery Using Wire Myography

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and drugs. It is widely used in many studies on the physiological functions of vascular smooth muscle, the pathogenesis of vascular diseases such as hypertension, and the development of smooth muscle relaxant drugs. The mouse is a widely used model animal with a large pool of disease models and genetically modified strains. We introduced this method to measure the isometric contraction of mouse mesenteric artery in detail. A 1.4-mm segment of mouse mesenteric resistance artery was isolated and mounted on a myograph chamber by passing two steel wires through its lumen. After equilibration and normalization steps, the vessel segment was potentiated by a high-K+ solution twice prior to the contraction assay. As an example of the application of this method in drug development, we measured the relaxant effect of a novel natural substance, neoliensinine, isolated from a Chinese herb, embryos of the lotus seed (Nelumbo nucifera Gaertn.) on mouse mesenteric arteries. The vessel segments mounted on the myograph chamber were stimulated with a high-K+ solution. When the force tension reached a stable sustained phase, cumulative doses of neoliensinine were added to the chamber. We found that neoliensinine had a dose-dependent relaxant effect on smooth muscle contraction, thus suggesting that it bears potential activity against hypertension. In addition, as the vessel segment can survive at least 4 hours after mounting and maintain contractility induced by the high-K+ solution for many times, we suggest that the wire myograph system may be used for the time-consuming process of drug screening.

The wire myograph technique is used to investigate vascular smooth muscle functions and screen new drugs. We report a detailed protocol for measuring the isometric contractility of the mouse mesenteric artery and for screening new relaxants of vascular smooth muscle.

Misurazione di contrattilità isometrica dell'arteria mesenterica Mouse con filo Myography

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and ...

Biventricular Assessment of Cardiac Function and Pressure-Volume Loops by Closed-Chest Catheterization in Mice

Assessment of cardiac function is essential to conduct cardiovascular and pulmonary-vascular preclinical research. Pressure-volume loops (PV loops) generated by recording both pressure and volume during cardiac catheterization are vital when assessing both systolic and diastolic cardiac function. Left and right heart function are closely related, reflected in ventricular interdependence. Thus, recording biventricular function in the same animal is important to get a complete assessment of cardiac function. In this protocol, a closed chest approach to cardiac catheterization consistent with the way catheterization is performed in patients is adopted in mice. While challenging, the closed chest strategy is a more physiological approach, because opening the chest results in major changes in preload and afterload that create artifacts, most notably a fall in systemic blood pressure. While high-resolution echocardiography is used to assess rodents, cardiac catheterization is invaluable, particularly when assessing diastolic pressures in both ventricles.
Described here is a procedure to perform invasive, closed chest, sequential left and right ventricular pressure-volume (PV) loops in the same animal. PV loops are acquired using&#160;admittance technology with a mouse pressure-volume catheter and pressure-volume system acquisition. The procedure is described, beginning with the neck dissection, which is required to access the right jugular vein and the right carotid artery, to the insertion and positioning of the catheter, and finally the data acquisition. Then, the criteria required to ensure the acquisition of high-quality PV loops are discussed. Finally, the analysis of the left and right ventricular PV loops and the different hemodynamic parameters available to quantify systolic and diastolic ventricular function are briefly described.

Presented here is a protocol to assess biventricular heart function in mice by generating pressure-volume (PV) loops from the right and left ventricle in the same animal using closed chest catheterization. The focus is on the technical aspect of surgery and data acquisition.

Valutazione biventricolare della funzione cardiaca e delle anse pressione-volume mediante cateterismo a torace chiuso nei topi

Assessment of cardiac function is essential to conduct cardiovascular and pulmonary-vascular preclinical research. Pressure-volume loops (PV loops) ...